Corrugated cardboard is commonly used in the manufacture of shipping cartons having a wide variety of uses. The manufacturing of corrugated cardboard and the manufacturing of the cartons themselves are both well known and form no part of the present invention. However, in the manufacture of corrugated cartons, it is customary to determine the compression strength of the corrugated carton by edge crush testing of precision cut samples that are typically of square or rectangular dimensions. Heretofore, such samples were cut by hand, such as with a razor, knife or saw, or formed with a die. However, precision cutting machines are now available to form precision cut samples of corrugated cardboard. An example of one such machine is disclosed in U.S. patent application Ser. No. 08/127,542, filed Sep. 28, 1993, now U.S. Pat. No. 5,423,238 entitled "Method and Apparatus For Precision Cutting of Corrugated Cardboard and Reference Rod Assembly Therefor," assigned to the assignee of the present invention.
Once the corrugated rectangular samples have been precision cut, it is then necessary to form cutouts or notches in parallel side edges thereof to define a center section of predetermined cross-section to establish a known failure or weak point where the sample will fail when subjected to a predetermined crush load during testing. In the industry, a pair of arcuate, semi-circular, or V-shaped notches are formed in the parallel side edges so that the resulting center portion has an hourglass-like configuration and a precise dimension of 1" in the center portion as measured between the two notches as in the case of a 2".times.2" sample. An example of a sample ready for edge crush testing is depicted in FIG. 2 of this application.
There are known cutting machines in the industry that are used to form cut-outs of arcuate or V-shape and one such machine generally utilizes a pair of razor blade type assemblies to cut the notches. Often, however, the sample is destroyed since the blades are incapable of cutting completely through the edge of the material. As the blades start to engage the respective edges, the second blade does not always reliably engage the second edge which simply causes the sample to be crushed, particularly in corrugated materials of lesser thickness.
Another known method for preparing rectangular samples for edge crush testing involves dipping in hot wax. The wax has to be a certain temperature and the corrugated material has to be partially immersed in the wax for a certain period of time. Deviations in either time or temperature result in uncontrolled migration within the sample. Furthermore, considerable time is necessary to enable the wax within the sample to dry and cure.
It is accordingly one object of the present invention to cut notches, with precision, in corrugated samples in an easy and reliable manner.
Another object is to cut notches within corrugated samples in a manner which result in sharp, not fuzzy, cut edges.
Still a further object is to notch corrugated samples in a reliable manner, irrespective of whether the sample is of one, two or three or more wall thicknesses.